Oxime insecticides

ABSTRACT

Compounds with anthropodicidal activities having the general formula (1) ##STR1## and their isomeric forms wherein R represents F, Cl, Br, ethoxy, methoxy or propxy and n is an integer between 1 and 5; or R represents 3,4-methylenedioxyl; and R 40  represents di- or trichloromethyl, fluorodichloromethyl or trifluoromethyl.

The invention relates to new 4-fluorophenoxy-benzyl ethers of oximes ofsubstituted phenyl halomethyl ketones, to a process for theirpreparation and to their use as arthropodicides, especially asinsecticides and acaricides.

Reference has been made in the literature to a general class of alkylaryl ketone oxime ethers of the general structure ##STR2## wherein X isone or more substituents, Y is an alkyl group and R-OH is the alcoholcomponent of active pyrethroid esters (Michael J. Bull et al., PesticideScience, 1980, 11, 249-256). The same reference discloses specifically alimited group of compounds falling within the broad class in which X is4-chloro, 4-fluoro or 4-methoxy, Y is methyl, ethyl, isopropyl,cyclopropyl or cyclobutyl and R is 3-phenoxybenzyl. Some of thesecompounds showed insecticidal activity. U.S. Pat. No. 4,079,149discloses a group of compounds of the same class in which thesubstituent X is one or two halogen atoms or alkyl or alkoxy groups andY is inter alia an alkyl group of two or more carbon atoms, optionallysubstituted with one or more halogen atoms and R is 3-phenoxybenzyl

U.K. Patent Application No. 2,025,407 discloses a similar group ofcompounds in which R is a 2,6-dihalobenzyl group. Neither of thesereferences, however, discloses any specific compounds in which the groupY is a halogenated alkyl group.

The present invention provides new compounds of the general formula (I)##STR3## wherein R represents F, Cl, Br, I, ethoxy, methoxy or propoxyand n is an integer between 1 and 5; or R represents 3,4-methylenedioxy;and R¹ represents di- or trichloromethyl, fluorodichloromethyl ortrifluoromethyl.

Preferred compounds are those where n=1 and R is in the 4-position onthe phenyl ring.

The compounds for formula I can exist in two possible isomeric formsknown as E and Z. Both isomeric forms are included in the invention.

The results of tests of insecticidal activity indicate that one isomericform has significantly greater activity than the other.

The more active isomers of compounds of the formula (I) aredistinguished by a powerful insecticidal and acaridical activity. Inparticular the compounds show powerful activity against cotton bud worm(Heliothis punctigera), an important agricultural pest.

The invention also provides methods for the production of the compoundsof the formula I. One method, which is similar to that described in ourcopending Australian Patent Application No. 83103/82, involves reactingthe appropriately substituted ketone or oxime of formula II ##STR4##wherein R, n and R¹ are as defined above, and X is=O withO-(4-fluoro-3-phenoxybenzyl)-hydroxylamine hydrochloride.

This reacton is relatively slow but in some instances may be appreciablyaccelerated by using temperatures above room temperature. In general thereaction is conveniently carried out by stirring the reactants at theselected temperature and at atmospheric pressure.

Another method, in accordance with the invention, involves reacting theappropriately substituted oxime (formula II; X is =NOH) with4-fluoro-3-phenoxybenzyl bromide.

The O-(4-fluoro-3-phenoxybenzyl)hydroxylamine hydrochloride can besynthesised from N-hydroxy-phthalimide, 4-fluoro-3-phenoxybenzylbromide, n-butylamine and HC1 by the method of Kaztreiner, Szilagyi,Kosary and Huszti described in Acta Chemica Academiae ScientarumHungaricae, 1975, 80, 167-180.

In some compounds the inactive isomer can be partly converted to theactive isomer by gently heating it in a polar solvent, e.g. methanol.The isomers can be separated by any conventional method, e.g., highperformance liquid chromatography (HPLC).

The active compounds are well tolerated by plants, have a favourablelevel of toxicity to warm-blooded animals, and can be used for combatingarthropod pests, especially insects or acarids, which are encountered inagriculture, in veterinary practice, in forestry, in the protection ofstored products and of materials, and in the hygiene field. They areactive against normally sensitive and resistant species and against allor some stages of development. The abovementioned pests include Luciliacuprina, Blatella germanica, and Heliothis punctigera.

The present invention also provides arthropodicial compositionscontaining as active ingredients a compound of the present invention.

The present invention also provides a method of combating anthropods(especially insects or acarids) which comprises applying to thearthropods, or to a habitat thereof, a compound of the present inventionalone or in the form of a composition containing as active ingredient acompound of the present invention.

The present invention also provides a method of freeing or protectingdomesticated animals from parasitical insects or acarids which comprisesapplying to said animals a compound according to the present invention,or a composition containing such a compound as the active ingredient.

In the compositions of this invention, the active compounds areconverted into such customary formulations as solutions, emulsions,wettable powders, suspensions, powders, dusting agents, foams, pastes,soluble powders, granules, aerosols, suspension-emulsion concentrates,seed-treatment powders, natural and synthetic materials impregnated withactive compound, very fine capsules in polymeric substances, and coatingcompositions for use on seed, as well as ULV cold mist and warm mistformulations.

These formulations may be produced in known manner, for example bymixing the active compounds with extenders, i.e., liquid or liquefiedgaseous or solid diluents or carriers, optionally with the use ofsurface-active agents, i.e., emulsifying agents and/or dispersing agentsand/or foam-forming agents. Where water is used as an extender,auxiliary solvents, such as for example, organic solvents, can also beused.

Examples of suitable liquid diluents or carriers, especially solvents,are aromatic hydrocarbons, such as xylene, toluene or alkylnaphthalenes, chlorinated aromatic or chlorinated aliphatichydrocarbons, such as chlorobenzenes, chloroethylenes or methylenechloride; aliphatic or alicyclic hydrocarbons, such as cyclohexane orparaffins, for example mineral oil fractions; alcohols, such as butanolor glycol, as well as their ethers; and esters, ketones, such asacetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone;and strongly polar solvents, such as dimethylformamide and dimethylsulphoxide, as well as water.

By liquefied gaseous diluents or carriers are meant liquids which wouldbe gaseous at normal temperature and under normal pressure, for exampleaerosol propellants, such as halogenated hydrocarbons as well as butane,propane, nitrogen and carbon dioxide.

Examples of solid carriers are ground natural minerals, such as kaolins,clays, talc, chalk, quartz, attapulgite, montmorillonite or diatomaceousearth; and ground synthetic minerals, such as highly-dispersed silicicacid, alumina and silicates. As solid carriers for granules there may beused crushed and fractionated natural rocks such as calcite, marble,pumice, sepiolite and dolomite; as well as synthetic granules ofinorganic and organic meals, and granules of organic material such assawdust, coconut shells, maize cobs and tobacco stalks.

Examples of emulsifying and/or foam-forming agents are non-ionic andanionic emulsifiers, such as polyoxyethylene-fatty acid esters, polyoxyethylene-fatty alcohol ethers, for example alkylaryl polyglycol ethers,alkyl sulphonates, alkyl sulphates, aryl sulphonates, as well as albuminhydrolysis products. Dispersing agents include, for example, ligninsulphite waste liquors and methylcellulose.

Adhesives such as carboxymethylcellulose and natural and syntheticpolymers in the form of powders, granules or latices, such as gumarabic, polyvinyl alcohol and polyvinyl acetate, can be used in theformulations.

It is also possible to use colorants such as inorganic pigments, forexample iron oxide, titanium oxide and Prussian Blue, and organicdyestuffs, such as alizarin dyestuffs, azo dyestuffs or metalphthalocyanine dyestuffs.

The formulations in general will contain from 0.1 to 99 percent byweight of active compound, preferably from 0.5 to 90 percent by weight.

The active compounds according to the invention may be used in the formof formulations of the types that are commercially available or in theuse forms prepared from these formulations.

The active compound content of the use forms prepared from theformulations of the types that are commercially available can varywithin wide ranges. The active compound concentration of the use formscan be from 0.0000001 to 100% by weight of active compound, preferablyfrom 0.01 to 10% by weight.

The compounds may be employed in a customary manner appropriate for theparticular use forms.

The active compounds according to the invention are also suitable forcombating ectoparasites and endoparasites in the field of veterinarymedicine. The compounds may be used in a known manner, such as orally inthe form of, for example, tablets, capsules, drenches and granules;dermally by means of, for example, dipping, spraying, pouring-on,spotting-on and powdering.

The compounds may be employed either as the sole toxic agent incompositions such as those described above, or in combination with otherinsecticides such as pyrethrum, rotenone, or with fungicidal orbactericidal agents, to provide compositions useful for household andagricultural dusts and sprays, textile coating and impregnation, and thelike.

In particular, the compounds of the invention may be advantageouslycombined with other substances which have a synergistic or potentiatingaction. Generally such substances are of the class of microsomal oxidaseinhibitors, i.e., they inhibit the detoxification of insecticides ininsects produced by the action of oxidative enzymes. Typical substancesof this type are the pyrethrin synergists of which the following areexamples:

[2-(2-butoxyethoxy)ethoxy]-4,5-methylenedioxy-2-propyltoluene (Piperonylbutoxide), 3-hexyl-5(3,4-methylenedioxyphenyl)-2-cyclohexanone(Piperonyl cyclonene),2-(3,4-methylenedioxy-phenoxy)-3,6,9-trioxaundecane (Sesoxane orSesamex), 1,2-(methylenedioxy)-4-[2(octylsulfinyl)propyl]benzene(Sulfoxide), dipropyl-5,6,7,8-tetrahydro-7-methylnaphtho-[2,3-d],3-dioxole-5,6-dicarboxylate (n-Propyl isome), as well as propynylethers, propynyl oximes, propynyl carbamates and propynyl phosphonates,and S,S,S-tributylphosphorotrithioates. ("Sesoxane", "Sesamex" and"Sulphoxide" are Registered Trade Marks).

Piperonyl butoxide is particularly useful as a potentiator. The amountof piperonyl butoxide used may vary from 1/100th to fifty times theweight of the compound I the preferred range being from about 1/100th tofive parts by weight. `Sesamex` also is a useful potentiator in similaramounts.

Examples of formulations in accordance with the invention are asfollows: (parts are by weight):

Dusts

The following substances are used to produce (a) a 5% dust and (b) a 2%dust:

(a)

5 parts of active substance,

95 parts of talcum;

(b)

2 parts of active substance,

1 part of highly dispersed silicic acid,

97 parts of talcum.

The active substance is mixed and ground with the carriers.

Granulates

The following ingredients are used to produce a 5% granulate:

5 parts of active substance,

0.25 part of epichlorohydrin,

0.25 parts of cetyl polyglycol ether,

3.50 parts of polyethylene glycol,

91 parts of kaolin

The active substance is mixed with epichlorohydrin and dissolved with 6parts of acetone, the polyethylene glycol and cetyl polyglycol ether arethen added. The solution obtained is sprayed onto kaolin and the acetoneis evaporated off in vacuo.

Wettable powders

The following constituents are used to produce (a) 1 40%, (b) and (c) a25%, and (d) a 10% wettable powder:

(a)

40 parts of active substance,

5 parts of sodium lignin sulphonate,

1 part of sodium dibutyl-naphthalene sulphonate,

54 parts of silicic acid;

(b)

25 parts of active substance,

4.5 parts of calcium lignin sulphonate,

1.9 parts of chalk/hydroxyethyl cellulose mixture (1:1),

1.5 parts of sodium dibutyl-naphthalene sulphonate,

19.5 parts of silicic acid,

19.5 parts of chalk,

28.1 parts of kaolin;

(c)

25 parts of active substance,

2.5 parts of isooctylphenoxy-polyoxyethylene ethanol,

1.7 parts of chalk/hydroxyethyl cellulose mixture (1:1),

8.3 parts of sodium aluminium silicate,

16.5 parts of keiselguhr,

46 parts of kaolin;

(d)

10 parts of active substance,

3 parts of a mixture of the sodium salts of saturated fatty alcoholsulphates,

5 parts of naphthalenesulphonic acid/formaldehyde condensate,

82 parts of kaolin,

The active substance is intimately mixed in suitable mixers with theadditives, and the mixture is then ground in the appropriate mills androllers to obtain wettable powders which can be diluted with water togive suspensions of the desired concentration.

Emulsifiable Concentrates

The following substances are used to produce (a) a 10%, (b) a 25%, and(c) a 50% emulsifiable concentrate:

(a)

10 parts of active substance,

3.4 parts of epoxidised vegetable oil,

3.4 parts of a combination emulsifier consisting of fatty alcoholpolyglycol ether and alkylarylsulphonate calcium salt,

40 parts of dimethylformamide,

43.2 parts of xylene;

(b)

25 parts of active substance,

2.5 parts of epoxidised vegetable oil,

10 parts of alkylarylsulphonate/fatty alcohol polyglycol ether mixture,

5 parts of dimethylformamide,

57.5 parts of xylene;

(c)

50 parts of active substance,

4.2 parts of tributylphenol-polyglycol ether,

5.8 parts of calcium-dodecylbenzenesulphonate,

20 parts of cyclohexanone,

20 parts of xylene.

Emulsions of the required concentration can be prepared from theseconcentrates by dilution with water.

Sprays

The following constituents are used to produce (a) 1 5% spray, (b) a 95%spray, and (c) a synergised 4% spray

(a)

5 parts of active substance,

1 part of epichlorohydrin,

94 parts of ligroin (boiling limits 160°-190° C.);

(b)

95 parts of active substance,

5 parts of epichlorohydrin;

(c)

4 parts of active substance,

1 part of piperonyl butoxide,

79 parts of deodorised kerosene,

16 parts of alkylated naphthalene.

The preparation and properties of the compounds of the invention areillustrated by the following specific examples. It should be noted, ofcourse, that these examples are intended to be illustrative of themethods and procedures utilized in preparing the compounds and that theyare not intended to be restrictive or to be regarded as embodying theonly way in which the compounds can be formed and recovered.

All temperatures are °C.

The O-(4-fluoro-3-phenoxybenzyl)-hydroxylamine hydrochloride used wasprepared as follows:

(a) N-(4-fluoro-3-phenoxybenzyloxy)phthalimide

N-hydroxyphthalimide (2.19, 0.018 mole) was dissolved in a mixture ofdry dimethoxyethane (15 ml) and dry dimethyl sulphoxide (4 ml). Theclear yellow solution was cooled to 25° and potassium carbonate (1.24 g,0.009 mol) was added. A red suspension resulted.4-Fluoro-3-phenoxybenzyl bromide (5 g, 0.018 mol) was added dropwiseover 5h at 22°-28°. The reaction mixture was stirred at room temperatureovernight, after which most of the dimethoxyethane was removed in vacuo,and the solution then quenched by pouring into dilute hydrochloric acid(100 ml 1%). The resulting slurry was filtered, and the crystals washedwith distilled water and dried in vacuo to giveN-(4-fluoro-3-phenoxybenzyloxy)phthalimide as white crystals (6.4 g),(98%), m.p. 88.2°.

Analysis: Found C, 69.6; H, 4.0; F, 5.3; N, 3.9%. C₂₁ H₁₄ FNO₄ requiresC, 69.4; H, 3.9; F, 5.2; N, 3.9%.

(b) O-(4-fluoro-3-phenoxybenzyl)hydroxylamine hydrochloride

N-(4-fluoro-3-phenoxybenzyloxy)phthalimide 5 g, 14 mmol), n-butylamine(1.13 g, 15 mmol) and absolute ethanol (3 ml) were placed in a dry flaskunder a nitrogen atmosphere. This reaction mixture was stirred at60°-75° for 1.5 hours, cooled and adjusted to pH 3 using dry hydrogenchloride gas. The solution was concentrated to 10 ml and poured into dryether. The resulting white precipitate was filtered off andrecrystallized from petroleum spirit (40°-60°)/dichloromethane to give3.2 g (87%) of a white solid, m.p. 149.3°.

Analysis: Found: C, 58.1; H, 5.1; Cl, 12.9; F, 7.0; N, 5.3%. C₁₃ H₁₃ ClFNO₂ requires C, 57.9; H, 4.9; Cl, 13.2; F, 7.0; N, 5.2%).

Oxime ether preparation - Method 1

Equimolar quantities of the ketone and theO-(4-fluoro-3-phenoxybenzyl)hydroxylamine hydrochloride were dissolvedin dry methanol (2.0 1/mol) and stirred at 10°-50° C. The reaction wasmonitored by thin layer or high pressure liquid chromatography andstopped when a satisfactory yield of product had been formed. Where theproduct was crystalline, it was isolated by filtration and purified byrecrystallization. For oily products the methanol was removed in vacuoand the residue chromatographed on silica gel to yield theoxime-O-ether.

Oxime ether preparation - Method 2

In an inert gas atmosphere sodium hydride (1.1 mole, 50% suspension inoil) was washed free of oil with petroleum spirit (30°-40° C.), dried invacuo and suspended in dry acetonitrile (1500 ml). To the stirredsuspension was added, dropwise a solution of the oxime (1.0 mole) in dryacetonitrile (500 ml). After 1 hour at room temperature a solution of4-fluoro-3-phenoxybenzylbromide (1.005 mole) in dry acetonitrile (500ml) was also added dropwise. The reaction was stirred at roomtemperature and followed by thin layer or high performance liquidchromatography. The reaction was stopped and the reaction mixture workedup when a satisfactory yield of product had been formed. The precipitatewas removed by filtration, the filtrate evaporated at 50° C. in vacuoand residue purified either by recrystallization or by chromatography onsilica gel to yield the desired oxime-O-ether.

Method 1 was used to make the oxime ether compounds of the followingExamples 1, 2 and 3.

EXAMPLE 1Dichloromethyl(4-ethoxyphenyl)methanone-O-(4-fluoro-3-phenoxybenzyl)-oxime(E and Z isomers)

NMR Spectral analysis indicated that the product was a 1:1 mixture of Eand Z isomers. The isomers were separated using high-performance liquidchromatography.

(a) E-isomer:

Analysis: Found: C, 61.6; H, 4.6; Cl, 15.6; F, 4.6; N, 3.2%. C₂₃ H₂₀ Cl₂FNO₃ requires C, 61.6; H, 4.5; Cl, 15.8; F, 4.2; N, 3.1%.

(b) Z-isomer:

Analysis: Found: C, 61.8; H, 4.7; Cl, 16.3; F, 4.4; N, 3.3. C₂₃ H₂₀ Cl₂FNO₃ requires C, 61.6; H, 4.5; Cl, 15.8; F, 4.2; N, 3.1%.

EXAMPLE 2 Dichloromethyl(4-cholorophenyl)methanone-O(4-fluoro-3-phenoxybenzyl)-oxime (E and Zisomers)

NMR spectral analysis indicated that the product was a 1:3 mixture of Eand Z isomers. The isomers were separated using high performance liquidchromatography.

(a) E isomer m.p. 50.6° C.

Analysis: Found C, 57.5; H, 3.3; Cl, 23.8; F, 4.3; N, 2.9%. C₂₁ H₁₅ Cl₃F NO₂ requires C, 57.5; H, 3.5; Cl, 24.2; F, 4.3; N, 3.2%.

(b) Z isomer

Analysis: Found C, 57.6; H, 3.4; Cl, 24.4; F, 4.1; N, 2.9%. C₂₁ H₁₅ Cl₃F NO₂ requires C, 57.5; H, 3.5; Cl, 24.2; F, 4.3; N, 3.2%.

EXAMPLE 3 Trichloromethyl(4-ethoxyphenyl)methanone-O-(4-fluoro-3-phenoxybenzyl)-oxime

NMR spectral analysis indicated that there was only one isomer formed.The product was purified by high performance liquid chromatography.

Analysis: Found C, 58.3; H, 4.1; Cl, 21.3; F, 3.8; N, 3.2%. C₂₃ H₁₉ Cl₃F NO₃ requires C, 57.2; H, 4.0; Cl, 22.0; F, 3.9; N, 2.9%.

The use of Preparation Method 2 is shown in the following Example.

EXAMPLE 4 (a) Trifluoromethyl(3,4-methylenedioxyphenyl)methanone

4-Bromo-1,2-methylenedioxybenzene (4.02 g, 0.020 mole) was dissolved indry diethylether (100 ml) and cooled to -30° C. under a dry argonatmosphere. At -30° C. to -40° C. n-butyllithium (12 ml, 0.002 mole;1.85 molar solution in n-hexane) were added with stirring over 15minutes. After 50 minutes at -30° C. the mixture was cooled to -50° C.and the solution of N-trifluoroacetyl piperidine (3.62 g, 0.020 mole) indry ether (20 ml) was added over 5 minutes. After 45 minutes at -50° C.the reaction mixture was warmed up to -40° C. for 30 minutes, and toroom temperature over another 30 minutes. Saturated aqueous ammoniumchloride (25 ml) was added with vigorous stirring. The layers wereseparated and the organic top layer washed with 10% aqueous ammoniumchloride (3× 50 ml) and dried over anhydrous sodium sulfate. Afterfiltration and removal of the ether under reduced pressure the residualliquid was distilled in vacuo to give trifluoromethyl(3,4-methylenedioxyphenyl)-methanone (2.2 g), (50.4%) b.p. 60° C./0.2 mmHg.

(b) Trifluoromethyl(3,4-methylenedioxyphenyl)methanone oxime

Trifluoromethyl(3,4-methylenedioxyphenyl) methanone (1.46 g, 0.0067mole), hydroxylamine hydrochloride (1.06 g), 0.015 mole) and sodiumacetate (0.86 g, 0.010 mole) were dissolved in a mixture of methanol (4ml) and water (4 ml) and heated to reflux for 4.5 hours. After coolingto room temperature, water (10 ml) was added and the mixture extractedwith ether (3×15 ml). The combined extracts were washed with water (20ml) and brine (20 ml) and dried over anhydrous sodium sulfate. Afterfiltration and removal of the solvent in vacuo the residue wasrecrystallized from a mixture of dichloromethane and petroleum spirit(40°-60° C.) to givetrifluoromethyl(3,4-methylenedioxyphenyl)methanone-oxime (1.2 g),(76.9%) m.p. 96.0° C.

(c)Trifluoromethyl(3,4-methylenedioxyphenyl)methanone-O-(4-fluoro-3-phenoxybenzyl)-oxime

Preparation Method 2 was used to make the title compound fromtrifluoromethyl(3,4-methylenedioxyphenyl) methanone oxime. NMR spectralanalysis indicated that there was only one isomer formed. The productwas purified by high performance liquid chromatography.

Analysis: Found C, 61.0; H, 3.5; F, 17.3; N, 3.6%. C₂₂ H₁₅ F₄ NO₄requires C, 61.0; H, 3.5; F, 17.5; N, 3.2%.

EXAMPLE 5

Insecticidal activity was investigated against blowfly, Lucilia cuprina.The method used was as follows:

(a) The compounds were tested for activity against a susceptible strainwhich had been collected in the field.

The test compound was applied in acetone solution, 0.5 μl dispensed witha Drummond micropipette to the dorsum of the thorax of 2-3 day oldfemales. Adult flies were fed on water and sugar-only and maintained at25° C. and 60-70% RH. The mortalities were determined after 48 hours.Moribund flies were regarded as dead. The LD₅₀ values, in terms ofconcentration, were interpolated from a probit/log dose graph using acomputer program.

(b) Potentiation

The compound was also tested on the insects described above inconjunction with the potentiator piperonyl butoxide by pretreating eachinsect with 1 μl of a 2% solution of the potentiator in acetone.

The mortalities were counted at 48 hours after treatment and comparedwith acetone and acetone/potentiator controls.

The LD₅₀ value was determined as described above.

About the same levels of potentiation were obtained when piperonylbutoxide was replaced by an equal amount of `Sesamex`.

Using the above-described techniques, LD₅₀ values were determined oneach of the compounds listed in Table 1.

Comparative tests were also carried out on a commercially availablesynthetic pyrethroid insecticide "Permethrin", i.e., the3'-phenoxybenzyl ester of3-(2',2'-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid,(mixture of 60:40 trans:cis isomers).

For ease of comparison the results obtained are expressed in Table 1, interms of a "potency index" given by ##EQU1##

The LD₅₀ for permethrin was determined concurrently with the LD₅₀ forthe test compound.

EXAMPLE 6

Insecticidal activity against the German cockroach (Blatella germanica)was determined using the following method:

The compound under test was applied in acetone solution at a range ofconcentrations. 0.5 μl was dispensed with a Drummond micropipette to theventral thorax of adult cockroaches. The mortalities were determinedafter 48 hours. Moribund cockroaches were regarded as dead. The LD₅₀values in terms of concentration were determined by probit analysis ofthe mortality/concentration data and converted to Potency Index values.

The results are shown in Table 1.

EXAMPLE 7

Insecticidal activity against the cotton pest Heliothis punctigera wasdetermined using the following method:

The compound under test was applied in acetone solution at a range ofconcentrations. 0.5 μl was dispensed with a Drummond micropipette to thedorsal surface of 3rd instar larvae. Each larva was held in a separatecontainer and was fed on spinach and maintained at 25° C. and 60-70% RH.The mortalities were determined after 48 hours. Moribund larvae wereregarded as dead. The LD₅₀ values in terms of concentration weredetermined by a probit analysis of the mortality/concentration data andconverted to Potency Index values.

The results are given in Table 1.

                  TABLE 1                                                         ______________________________________                                        INSECTICIDAL ACTIVITY                                                         Compound of                                                                            Potency Index Against                                                Example  Lucillia cuprina                                                                              Blatella  Heliothis                                  No.      (alone)  (+potent.) germanica                                                                             punctigera                               ______________________________________                                        Permethrin                                                                             100      100        100     100                                      1(a)     140      21         1400    985                                      (E isomer)                                                                    1(b)     71       72         940     640                                      (Z isomer)                                                                    2(a)      6        4          54                                              (E isomer)                                                                    2(b)     10       17          12                                              (Z isomer)                                                                    3        17        8         <8                                               4         4        2         <8                                               ______________________________________                                    

I claim:
 1. A compound of formula (I) ##STR5## wherein R represents F,Cl, Br, I, ethoxy, methoxy or propoxy and n is an integer between 1 and5; or R represents 3,4-methlenedioxy; and R¹ represents di- ortrichloromethyl, fluorodichloromethyl or trifluoromethyl and a E or Zisomer thereof or a mixture of these isomers.
 2. A compound as claimedin claim 1, characterized in that n is 1 and R is in the 4-position onthe phenyl ring.
 3. Trichloromethyl(4-ethoxyphenyl)methanone-O-(4-fluoro-3-phenoxybenzyl)-oxime. 4.Trifluoromethyl(3,4-methylenedioxyphenyl)methanone-O-(4-fluoro-3-phenoxybenzyl)-oxime.5. An arthropodicidal composition which comprises as an activeingredient an arthropodically effective amount of a compound of theformula (I) as claimed in claim 1 in admixture with a veterinarianacceptable diluent or carrier.
 6. A composition as claimed in claim 5,which also includes at least one substance which has a synergistic orintensifying effect on pyrethroids and which is a microsomal oxidaseinhibitor.
 7. A composition as claimed in claim 6, wherein the substanceis selected from propynyl ethers, propynyl oximes, propynyl carbamates,propynyl phosphonates, S,S,S-tributylphosphorotrithioates,[2-(2-butoxyethoxy)ethoxy]-4,5-methylenedioxy-2-propyltoluene (Piperonylbutoxide), 3-hexyl-5(3,4-methylenedioxyphenyl)-2-cyclohexanone(Piperonyl cyclonene),2-(3,4-methylenedioxy-phenoxy)-3,6,9-trioxaundecane (Sesoxane orSesamex), 1,2-(methylenedioxy)-4-[2-(octylsulfinyl)propyl]-benzene(Sulfoxide), anddipropyl-5,6,7,8-tetrahydro-7-methylnaphtho[2,3-d]3-dioxole-5,6-dicarboxylate(n-Propyl isome).
 8. A composition as claimed in claim 7, wherein thesubstance is present in the composition in an amount of from 1/100th tofifty times the weight of the compound of formula (I).
 9. A compositionas claimed in claim 7, wherein the amount is from 1/100th to five timesthe weight of the compound of formula (I).
 10. A method of combatingarthropods which comprises applying to the anthropods, or to a habitatthereof, an effective amount of the composition of claim
 5. 11. A methodof freeing or protecting domesticated animals from parasitical insectsor acarids which comprises applying to said animals an effective amountof the composition of claim
 5. 12.Dichloromethyl(4-ethoxyphenyl)methanone-O-(4-fluoro-3-phenoxybenzyl)-oximeor its E or Z isomer, or a mixture of these isomers. 13.Dichloromethyl(4-chlorophenyl)methanone-O-(4-fluoro-3-phenyxoybenzyl)-oximeor its E or Z isomer, or a mixture of these isomers.